Ocean Secrets
by BadgerLALA
Summary: Sherlock is down by the south coast of England for a case. There he meets a merman imprisoned in an aquarium research centre. The merman's name is John.
1. Blue Scales

It was in the middle of the night when Sherlock came out of his hideout inside the aquarium and marine research centre. The aquarium was located on the south coast of England and Sherlock was here to investigate the mysterious death of a man named Rupert Dawson. Mr Dawson had worked at the aquarium alongside the awarded marine professor James Moriarty. Two days before his death Mr Dawson had contacted the Scotland Yard telling them that he had compelling evidence against Professor Moriarty. He was expected to arrive in London a few hours later but of course he never did. Sherlock had sighed annoyed when he had heard this. Why can't just people keep their mouth shut? If would have been much easier if Mr Dawson had just showed up with his so called compelling evidence, at least he wouldn't be dead.

Two days later Mr Dawson was found dead on the beach. At first glance it had had looked like he just taken a swim in the ocean, got caught in an undertow and drowned. It was here Sherlock spotted the first error. Mr Dawson had been a good swimmer and he had known that water very well so he of all people would know about the dangerous undertow. No, someone wanted him dead and they made it to look like an accident. So now Sherlock had to find out what Mr Dawson had found against Professor Moriarty. It must be something really serious if Moriarty would go so far that he would murder a man.

Sherlock hadn't needed to break inside. He had just simply walked in when the aquarium had been open to the public. When no one saw he sneaked inside a locked supply room (which he just happened to have the card key to) and hid there until the centre closed for the day and everyone had left for home.

oOo

A blue light was filling the main room where the big water tank with various sharks was. The only sounds you heard was the purl of water and the distance buzz from the water pumps. Sherlock knew he wouldn't find anything of interest here. He needed to get inside the part of this place where the public didn't have access and there he knew he would find what he was looking for. Earlier during the day Sherlock had located a door with a "staff only" sign next to the smaller tank with rays. He used the key card and entered. When he shut off the alarm he noticed a different sound other than the buzzing from the pumps. It sounded like, no it was impossible, someone was singing. It didn't make any sense to Sherlock. No one was supposed to be here. He must look this up.

Sherlock carefully started to move towards the singing. First he passed a long corridor but where it ended he entered a room full of water tanks. This must be the research part. The room wasn't well lit. The only light Sherlock had was the bluish light from the tanks. Each tank was between 5 to 6 meters wide and had no ocean floor inspired inside like the tanks the public got to see. Here it was just plan holding tanks for research purpose. As Sherlock got further and further inside the building the song grew stronger. It sounded like a sad song and it was hard to tell if it was sung by a man or a woman. Sherlock had never heard anything like it before. To tell the truth he wanted to say it sounded like nothing from this earth.

When the song was at its peak he had gotten to the back of the research area. Sherlock looked around for the source of the music but didn't see anyone. The only thing he noticed was that it seemed like the sound came from the biggest tank in the room. The tank was about 7 by 7 meters and wasn't very lit. Sherlock couldn't see if there was anything inside it. He stepped closer but as he did this the song stopped. Now it really caught Sherlock attention so he stepped ever further towards the tank to get a better look. Nothing at this point made any sense to Sherlock. He got even closer to the tank with its mysterious content. His face was only half a meter away from the glass when he finally was able to see the silhouette of the sea creature in the tank. It was a big creature but he didn't recognize it. What was Moriarty keeping here?

"What are you?" Sherlock asked himself. He took a step back and searched for a light switch so he could see the creature better and identify it. He found the switch but what he saw as the light lit up inside the big tank wasn't something he had expected.

When Sherlock had been only a boy he had read a lot of stories about pirates. Often in these stories were mermaids mentioned, creatures that looked half human and half fish, which used to lure seamen into the depth with its songs. A story amongst others but now this story felt really real as his saw one in the flesh right in front of him. Sherlock couldn't believe his eyes, there was a mermaid (or merman as it was obviously a male one) looking back at him with its ice blue eyes. The merman had short brown blond hair and what looked like human skin flecked with scales. He looked almost human. The merman also had a big scar on his left shoulder. Waist down was a completely different story. Here, just like in the stories, the merman had a long shimmering dark blue scaly fish like tail. As Sherlock was studying it he realised it was studying him back.

"What are you and what have Moriarty been up to?" he said to himself and looked on the merman. Did the merman have something to do with the death of Rupert Dawson? Right now there were more questions than answers and that made Sherlock frustrated. In that moment the merman caught Sherlock attention. He was pointing towards something next to his tank. First he didn't understand what he meant, but then Sherlock noticed that just above the light switch he had used earlier sat a microphone. He pointed at it and the merman nodded. Sherlock walked over the microphone and pushed the button.

"Hello…?" Sherlock asked and waited.

* * *

**A/n: I'm back! :D This time with another AU story where John is a merman. I hope you like it. :) If you want the latests news about my fics I'm on Tumblr (username on my profile) Also big thanks to my new beta reader Kajsa :) **


	2. Orange Light

"Hi there, who are you? You don't look like someone working here," the merman said through the speaker system next to his tank. Just seconds before Sherlock had been filled with thoughts but as the merman spoke his mind went almost blank. Nothing of this made any sense to him. This merman shouldn't even exist.

"Uhm, no, I don't." Sherlock didn't really know what to say. What do you normally ask/say to a merman?

"I'm John. What's your name?" John said and smiled.

"John? I wasn't expecting that as a name, I thought you would be named something more… uhm… unusual." Of all the things Sherlock could have said he said that. So stupid, of course his name could be John.

"Did you expect a more Greek sounding one?" John said with a hit of sarcasm in his voice.  
"I'm Sherlock."

"Unusual name for a human." A few seconds of awkward silence followed before Sherlock spoke.

"Was it you that sang?" The first of many questions Sherlock had.

"Ah yes, I guess you heard that," John said and sighed.

"Why?" Sherlock asked, questioning.

"Because I have nothing better to do while passing my time. You would do that too if you where locked inside a glass prison with nothing to do."

"Glass prison?" Sherlock asked and his eyes automatically moved towards the top of John's tank. "Oh," Sherlock said in a low voice when he finally realised what John had meant with glass prison.

John's tank was about 10 metres tall but the water only reached 6 meters up. Here it was a small platform as long as the tank but only two meters wide. The only access to the tank was a solid door, which was most likely both locked and alarmed.

"See, I told you it was a prison. Other than swim around or sit on the bottom I have nothing to do. The only thing that prevents me from going mad is to sing. Singing is second nature to me. It is to all merpeople." Sherlock turned back his attention towards the merman.

"Why are you telling me all this? You don't even know who I am."

"I don't know," said John and shrugged. "It just felt like I could trust you. But I would still like to know what you are doing here in the middle of the night."

"I'm here to investigate the death of a Rupert Dawson."

"He is dead?! Oh no, how sad," John sighed sadly and shook his head. Then he continued: "So you are a policeman then?"  
"No, I'm a consulting detective."

"I have no idea what that is. I know a lot about humans but I have never heard anything called a consulting detective," John said and looked at Sherlock with interest.

"Well, I'm the only one in the world, I invented the job. So are you the only one in the world, merperson I mean?" Sherlock knew he was here to find out more about Rupert Dawson but he just had to ask that question.

"Oh no, there are more of us. It's just I'm the one that got caught. Because of my-"  
"Your shoulder", John and Sherlock said at the same time.

"Obviously."

"But that doesn't mean I'm not a good swimmer just because I got caught. I know that's what you are thinking but I…" But John didn't have time to finish his sentence before Sherlock interrupted.

"It doesn't matter right now. Do you know anything about Mr Dawson's death? You seemed to know who he was," Sherlock continued.

"Yes, Rupert was the only one who was kind to me here. He saw me as an equal, not just as a sea creature in a tank as many did. Rupert didn't like Moriarty's plan."

"What plan?" Finally Sherlock was getting somewhere.

"His plan to…"

"Hello, anyone here?" An unknown male voice was heard and both Sherlock and John turned towards it. It came from the entrance to the research area.

"It's the security guard." John turned to Sherlock and whispered: "Hurry! You must leave. Please." Sherlock opened his mouth to say something but he changed his mind and nodded. It was too early into the case for him to get caught.

"Bye, Sherlock," John whispered as Sherlock started to move away. Sherlock knew he couldn't use the same way as he came in but he remembered seeing a fire escape door only meters away on the planning for the centre. Sherlock heard how the security guard got closer and Sherlock saw light from his torch moving around as he searched for possible intruders. Sherlock didn't have much time to spare until the guard had reached John's tank. But Sherlock couldn't help to turn towards John's tank. There he saw John was looking towards him. His right palm was pressing against the glass and he looked very sad. This was the last image Sherlock saw of John before he left through the door.

oOo

Sherlock was now at his hotel room. He sat in the bed leaned against the wall with his fingertips pressed together and eyes closed. He had been reflecting over the Rupert Dawson case all night. His room was filled with orange light as the sun had just started to peek up from behind the horizon but Sherlock did care or hadn't even noticed. He had thought from every angle of the case but his thoughts had kept returning to John. Why was John kept there and why hadn't Moriarty gone public? A normal scientist would go public with his find and get all kinds of fame and glory. Finding a merman would certainly make you world famous. What was Moriarty's plan that Mr Dawson didn't like? It must be because of this plan he got murdered. But why? Sherlock sighed frustrated. Then Sherlock realised he needed to get back to the aquarium and see John. John must hold the key to this case. He knew what Moriarty's plan was and this would lead to why Mr Dawson was murdered. The deeper Sherlock got in this case the stranger it got. Sherlock would got and see John tonight. Until then he need to do some research about merpeople.


	3. Ice Blue Eyes

After one hour researching merpeople Sherlock stopped. Everywhere he looked he read about the same thing (just in different versions). Basically they all said:_ Merpeople look half human half fish and they could lure and attract humans with their enchantingly beautiful, soft melodic and seductive siren-like singing voices and tones_. _In some folk traditions they could be devoted to or even fall in love with humans._ Of course there were more facts but filling his head with such nonsense felt so pointless. Most of the information Sherlock found was only based on pure myths and legends. Now Sherlock had yet another reason to see John. He didn't need the Internet to provide him with information about merpeople. Sherlock could just ask the real deal himself if he so pleased. So instead Sherlock started to research more about Professor James Moriarty. This professor had kept on popping up throughout this case.

Everywhere Sherlock read Moriarty was praised for being a genius within marine biology. He was the youngest to have won so many awards for his research. If there had been a Nobel Prize for marine biology Moriarty would surely had won it. After some more digging he found out some academics had accused Moriarty of stealing others researches and finds. But this had later been withdrawn by the same academics and they had apologized.

Sherlock found this odd, but at the same time he wasn't surprised. If Moriarty could get Mr Dawson murdered he could easily threaten those scientists. Something was up. Even if Moriarty was a genius he couldn't simple have the time to work as hard as he did. It wasn't humanly possible. There was one thing that Sherlock found that stood out. It was that time Moriarty had been on a world tour for half a year talking about his latest find when only a week after his return to England he had presented a new find of his. No one could be that good. The only way Moriarty could have made that possible was to steal somebody else's work. Sherlock had a theory but he needed John to get the final pieces into place.

oOo

When the night came Sherlock found himself once again walking in the bluish light of the closed aquarium. When he left the public parts of the centre he heard John sing in the distance. It sounded even more beautiful today than yesterday. He could just stand there and listen to it for the rest of the night, or possibly his life. 'No, focus, Sherlock, you have a case to solve,' he snapped to himself and continued to walk towards John's tank.

John burst out in a big smile when the lights turned on in his tank and he saw Sherlock. Sherlock saw how John's lips moved and formed his name. John looked both happy and surprised to see him.

"Sherlock, I'm so glad to see you," John said as Sherlock put on the speakers.

"John, I need you to tell me what Moriarty's plan is."

"Hold your seahorses, Sherlock, you haven't even said hello."

"Now, John!" Sherlock snapped annoyed. He didn't have the time for unnecessary chit-chats. John's smile disappeared and he almost looked insulted.

"Hey, if that's the tone I won't tell you. You can go a find yourself another merman that's willing to listen to your rudeness," John crossed his arms and took a few small strokes with his tail so he started to move upwards.

"No, John, wait. I'm sorry. Please come back."

"Very well, since you asked so nicely," John said and sank back down to Sherlock's level. "But I'll only tell you about Moriarty's plan if you tell me more about what you do as a consulting detective."

"Fine," Sherlock said and sighed. What a sneaky little merman John was. But okay, Sherlock would play it his way, he needed that crucial information from John. "When the police are out of their depth, which is always, they consult me. I use my sense to pick up details and I deduce from that. Like I can tell a software designer by his tie or an airline pilot by his thumb."

"Fantastic," John said amazed. "Can you deduce me?"

"Other than your scar on your shoulder was made by a harpoon I can't deduce much. I have never deduced a merman before."

"Ah yes, that one I got when I tried to save a fisherman who had fallen off his boat. His friends thought I was a shark." John was quiet for a few seconds, then spoke again. "I guess you want to know about Moriarty's plan then."

"If you don't mind," Sherlock said politely.

"Moriarty's plan is that he wants to capture more merpeople. One isn't enough for him. He wants me to tell him where he can find the rest of us but I won't tell him. Moriarty can't force the answer out of me. He wouldn't dare to hurt his only specimen. When Rupert heard this he got cross. He didn't want Moriarty to capture more of us and sell us to zoos and such things. Merpeople should be free, not captured like animals. I heard Rupert threat Moriarty that he would expose him as the fraud he really was. That was the last time I saw Rupert."

"Oh," Sherlock said lowly. Finally everything made sense. "Thank you John, you are brilliant!" Sherlock said excitedly. John had the key to this case. _He_ was the key. Sherlock turned towards the exit door. No time to loose, he needed to report this back to London.

"Wait! Are you already leaving?" John said almost shocked. "But you'll come by tomorrow, right?" Sherlock turned back to John. "Please." John looked on Sherlock with pleading ice blue eyes. His hand was pressed upon the glass. Why should Sherlock return tomorrow? The case was done and he didn't really need more information from John. But it was something with John that made him want to see him again. Before Sherlock mind had caught up with him he had pressed his hand over John's and had agreed to return tomorrow. When smiles had been exchanged Sherlock turned and walked away leaving through the nearest door.

* * *

**A/N: I just wanted to tell you there is now a Russian translation of this fic. It's made by the awesome doctorbarty and you can find the link to it on my account. :)**


	4. White Landscape

_The fog was so thick around Sherlock that he couldn't even see as far as his own hands in front of him. Helpless he wandered in this white landscape completely confused. Everywhere he looked was this great white wall. He had walked for what felt like hours when something broke the silence. Someone was singing with unusual tones. Wait, Sherlock recognized that voice. It was John's! Sherlock made a sigh of relief. He started following the sweet melody through the fog. What else could he really do? The music grew in intensity as he walked closer and closer. Then finally he broke out from the fog. He found himself standing on a sunny beach. Sherlock looked around and there, on a rock by the water's edge, sat John. The sun reflected in his scales and they cast blue reflections all over the place. It was the first time Sherlock realized how beautiful John really was. John was really one of nature's wonders. John stopped singing and smiled warmly towards Sherlock. Sherlock started to walk towards John, he almost ran. John jumped down from his rock down on the sand. When Sherlock came up to John he sat down on his knees so they were on eyelevel. They looked each other in the eyes and Sherlock reached out a hand and cupped John's face.  
_

"_You're so beautiful," Sherlock said softly and stoked his thumb over John's cheek. John smiled shyly. That was it! Sherlock couldn't resist anymore. He leant toward and kissed John on the lips. When John answered the kiss Sherlock pulled him closer. They lay down on the sand, John on top of Sherlock. The kiss deepened. Sherlock ran his hands over John, mapping his scaly beautiful body and he felt John doing the same to him. He wanted to feel, smell and taste every single part of John's body. Sherlock didn't want this moment to ever end. It felt like he just could die right here right now in John's arms and he would be so happy. _

_When kiss was the most heated and they were the most entangled in each other a dark shadow fell over John. John broke away from the kiss and looked up. Every single ounce of happiness disappeared from John's expression and was replaced with fear. Sherlock started to turn around to investigate what had made this sudden change of John. This was a big mistake. As soon as he started to turn he felt John getting ripped away from his arms. _

"_Sherlock!" John screamed in panic. Sherlock was quick on his feet but when he turned and looked for John he was nowhere to be seen. Sherlock stood in the only sunny place with fog all around. _

"_John!" he shouted aghast._

"_Sherlock! Sherlock, help!" Sherlock turned towards the sound. It came from right inside the fog. Of course it would. He didn't hesitate and ran inside the fog after John. He didn't want to lose John. _

"_John!" he shouted, but no answer. _

"_John!" he shouted against this time more hit of panic. Still no answer. The longer he walked the more it looked like the fog around him got thicker and thicker. With every breath he took it became harder and harder to breathe. He didn't get any oxygen in his lungs. Sherlock started to gasp for air. But he didn't want to give up. He needed to find John. After a while he collapsed on the ground. It felt like he was suffocating. _

Sherlock sat straight up in his bed, gasping for air. The sweat was running down his body and he was breathing hard. It had just been a dream. He sighed and put his head in his hands. The thoughts were spinning in his head. He had worked so hard to shut off any emotions but still they crept inside his dreams. Sherlock moved up a hand and touched his lips. He could still feel the ghostly remains of John's lips there. Damn it, his body was betraying him! Sherlock sighed and ruffled his hair. He needed to cool himself off. As he swung his legs over the edge of the bed Sherlock realized how hard he was. Bloody hell! How could John had gotten to him like this? It didn't make any sense to him right now. He stood up and wrapped bed sheet around himself. Out on the small half circle shaped balcony Sherlock stood and looked out over the ocean. It would be at least one more hour before the sun would begin to come up. It was the beginning of a new day and tonight he would see John again.

oOo

For the third time Sherlock found himself walking into the closed aquarium after dark. It had almost become a routine. The music hit him as he walked towards John's tank. The song was happy compared to the one Sherlock had heard the first night he was here. Was this because John was expecting him? It was the only possible explanation.

When Sherlock put on the light in the tank John almost glowed of happiness.  
"Hello, John," Sherlock said and put his hand on the glass. John swam over and put his hand over Sherlock's.

"More polite to day, eh?" John said and chuckled. Sherlock chuckled too. But this happy reunion came to a sudden halt when Sherlock felt a beefy arm around his neck. It pulled him a few meters away from the tank. Sherlock tried to fight loose but the arm held him in a firm grip. It was when Sherlock felt the barrel of a gun against his temple that he stopped fighting.

"Let him go!" John shouted and hammered with his fists on the glass over and over again.

"Well, well, look what the catfish dragged in," the man holding Sherlock said in a Scottish accent.

"Eddy dear, what have I told you about jokes like that?" A second man said disappointed as he stepped out from his shadowy hideout next to John's tank.

"Sorry, boss," Eddy apologized. Sherlock recognized the man Eddy was referring to as 'boss'. He had seen photos of this well dressed man on the Internet. It was Professor James Moriarty himself.


	5. Silvery Colour

Moriarty walked over to Eddy and Sherlock. He stopped just a meter away from them.

"Three nights you have come here." Moriarty started to walk back and forth. "Did you think I would be so stupid that I wouldn't notice an intruder? I know of every single person that comes in and out of here. I even have surveillance cameras installed that only I know about. The only reason you got the chance to return two more times was because I let you. I was quite fascinated that you got my little goldfish to talk. He hardly talks to anyone." Moriarty stopped and bent towards Sherlock and whispered: "I think he's got a bit of a trust issue." Moriarty straightened up and continued to talk in his normal tone. "Now tell me, my dear intruder. Who are you and what is your business here? I highly doubt it's for a private tour at the aquarium."

"I'm Sherlock Holmes and I'm here to investigate the death of Rupert Dawson. I know he threatened to expose the fact that you have stolen other scientists' researches just because he didn't like your plan to capture more merpeople."

"Oh. Seems a little birdy have told you. Or should I say fish?" Moriarty said and gave John a quick glare before turning back to Sherlock. "Too bad you won't have any use for that information."

"Let me guess. You'll murder me but you will stage it so that it will look like an accident just like you did with Mr Dawson"

"Something like that, yes. But I won't spoil the fun by telling you," Moriarty said a grinned evilly.

"No, please don't hurt him! I beg you," John shouted in distress. Moriarty turned towards John.

"What's that Fish boy? Do you care for this human?" he asked and smiled in a sinister way. Without warning Moriarty punched Sherlock in his stomach knocking the air out of him. Sherlock coughed and choked out a small moan.

"Stop it!" John shouted. Moriarty just chuckled.

"Well look at that. By the look of you it seems you have fallen in love with him. Oh, this is too good to be true," Moriarty said cheerfully. "Oh, Eddy!" On that cue Eddy let go of Sherlock and punched him right in the face. The punch had such force that Sherlock landed and slid on the floor further away from the tank. Sherlock tried to sit up but he was too dizzy at the moment. He felt that he was bleeding from his nose.

"NO!" John screamed in agony. "Stop this madness!"

"Not until you tell me where I can find the rest of you people," Moriarty said ice cold.

"You can ask me anything but that. I can't tell you."

"Oh, too bad." Moriarty snapped with his fingers and Eddy started walk towards Sherlock on the floor. Eddy put away his gun and cracked his knuckles.

"Tell where I can find them or I'll make him suffer," Moriarty said to John.

"NO!" John shouted furiously. Then he started to scream loudly and shrilly. Eddy stopped in his track and covered his ears.

"Sorry boss, it's too loud. I can't handle this, it feels like my head is gonna explode," Eddy said almost like he was in pain and fled from the building.

"You coward!" Moriarty shouted after him but it drowned in John's scream. Then he turned towards John. "Shut up!" But John didn't shut up; he started to scream even loader. Now Moriarty had to cover his ears too. Sherlock did the same but it didn't do much difference. The loud noise made it hard to think and your head was pounding. If was in that moment Sherlock noticed the crack in the glass of John's tank. Oh, clever John. If anyone could break the glass of the tank with the voice it would be John. When Sherlock had made sure he was far away enough for the big finale he watched as the crack grew wider. Then the tank glass burst and the water hit Moriarty will full force. Moriarty hadn't noticed the crack until it was too late and he died by the impact of the water. When everything was over Sherlock got up and walked towards John. He sat on the floor looking a bit dazed from being flushed out on the floor. There was a small cut on his cheek and tail but other than that he was unharmed. Sherlock crouched in front of John.

"Are you okay?" Sherlock asked.

"Yes, fine. And you?" John smiled to him.

"Yes. Come on, let's get you out of here." Sherlock lifted John up in his arms. He looked one last time over on Moriarty's body before they left the building and walked out into the night.

oOo

Sherlock and John arrived at the beach. Outside it was a starlit night and the moon was almost full which reflected in the water lighting up the place in a blue silvery colour. Sherlock let John down at the water's edge. He chewed on his bottom lip before he finally spoke.

"I guess this is good bye, then."

"Seems like it." John looked down on the ground. Half a minute of silence fell between them and the only thing you heard was the sound of the waves moving back and forth.

"What Moriarty said back at the aquarium, had you really fallen in love with me?" Sherlock anxiously awaited John's answer. John looked up into Sherlock eyes.

"Yes. I mean, how couldn't I? You are one remarkable human. You're a consulting detective with the power to deduce people. Absolute extraordinary!" Sherlock felt how he blushed. He hadn't blushed in years. Sherlock felt how his emotions were taking over but this time he let them.

"John, I have fallen in love with you too. But how can we be together? You need to be in the ocean and I on land." Sherlock sighed sadly and looked away. This was why Sherlock tried to avoid feelings. Often they would only hurt. John put his finger underneath Sherlock's chin and turned Sherlock towards him again.

"Sherlock, there is a way." John looked Sherlock deep into his eyes.

"How? There is no possible solution."

"There is. You see, merpeople can turn into humans but once they have done that they can never turn back to their original form."

"Would you do that for me?"

"Yes," John said and smiled. Sherlock just gave a sigh that was a mix of surprise and happiness. He felt moved. John was really going to give up his life in the ocean for him. John moved a little away from Sherlock, and then he started to chant in a different language. There, right in front of Sherlock eyes, he saw how John's body slowly started to change from merman to human. After five minute John stopped chanting and he fell exhausted forwards but Sherlock was there to catch him. He took John in his arms and looked at him. John looked fully human except for that his eyes were a bit bluer than found in regular humans.

"Have I ever told you that you are brilliant?" Sherlock asked.

"Yes, one time before," John said and chuckled. Sherlock smiled, then he leaned toward and kissed John. John kissed him back. This time the kiss wasn't a dream. It was the real deal.

* * *

**A/N: The End. Thank you for reading. Please review and fav.**


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